The development of the human visual system's spatial resolving capacities has been previoulsy studied in infants through measures of grating acuity and contrast sensitivity. However, adults are capable of making spatial discriminations (spatial interval discriminations, vernier offset discrimination, orientation discrimination, and stereoacuity) which are approximately an order of magnitude better than the minimum angle of resolution measured by Snellan or grating acuity. In addition to representing the finest measure of the human visual system's spatial resolving capacity, these hyperacuities (Westhemier 1975) or precise position acuities may offer a better method for the early identification of infants and young children with vision abnormalies. The proposed studies are designed to 1) investigatae the development of several hyperacuities over the first 6 years of life using behavioral techniques 2) develop better methods of clinically assessing visual function in infants and young children through behavioral measures of hyperacuity and 3) apply an electrophysiological technique, the visually evoked potential, to the study of the development of hyperacuity and its clinical assessment in infants and young children. Improvements in the clinical assessment of visual function in infants and young children through noninvasive behavioral and electrophysiological procedures will aid the clinician in early identification of vision anomalies and provide better methods for monitoring regimes.